1. Effects of pulsating flow on convective heat transfer in a two-dimensional wavy passage are investigated numerically. Three channels with wavy walls and phase shift of φ=0o,90o and 180o between bottom and top walls are considered. Phase angle between walls is adjusted by moving the lower wall while the upper wall is kept stationary. Two-dimensional and unsteady form of Navier-Stokes and energy equations is utilizied in order to simulate the flow and temperature fields in the channels and solved by the ANSYS FLUENT commercial code utilizing SIMPLE algorithm. Simulations are performed for three different pulsating frequencies and two different oscillating amplitudes. In all cases the Reynolds number (Re=100) and Prandtl number (Pr=7,0) are kept constant. The results obtained demonstrate that oscillatory flow has strong effects on convective heat transfer. The channel geometry, oscillation frequency and amplitude significantly affect the flow pattern and temperature structure in the channel.